In recent years, a significant industry has developed which involves the application of customer-selected designs, messages, illustrations, and the like (referred to collectively hereinafter as “customer-selected graphics”) on articles of clothing, such as T-shirts, sweat shirts, and the like. These customer-selected graphics typically are commercially available products tailored for a specific end-use and are printed on a release or transfer paper. The graphics are transferred to the article of clothing by means of heat and pressure, after which the release or transfer paper is removed.
Heat transfer papers having an enhanced receptivity for images made by wax-based crayons, thermal printer ribbons, and impact ribbon or dot-matrix printers, are well known in the art. Typically, a heat transfer sheet comprises a cellulosic base sheet and an image-receptive coating on a surface of the base sheet. The image-receptive coating usually contains one or more film-forming polymeric binders, as well as, other additives to improve the transferability and printability of the coating. Other heat transfer sheets comprise a cellulosic base sheet and an image-receptive coating, wherein the image-receptive coating is formed by melt extrusion or by laminating a film to the base sheet. The surface of the coating or film may then be roughened by, for example, passing the coated base sheet through an embossing roll.
Much effort has been directed at generally improving the transferability of an image-bearing laminate (coating) to a substrate. For example, an improved cold-peelable heat transfer material has been described in U.S. Pat. No. 5,798,179, which allows removal of the base sheet immediately after transfer of the image-bearing laminate (“hot peelable heat transfer material”) or some time thereafter when the laminate has cooled (“cold peelable heat transfer material”). Moreover, additional effort has been directed to improving the crack resistance and washability of the transferred laminate. The transferred laminate must be able to withstand multiple wash cycles and normal “wear and tear” without cracking or fading.
Various techniques have been used in an attempt to improve the overall quality of the transferred laminate and the article of clothing containing the same. For example, plasticizers and coating additives have been added to coatings of heat transfer materials to improve the crack resistance and washability of image-bearing laminates on articles of clothing. However, cracking and fading of the transferred image-bearing coating continues to be a problem in the art of heat transfer coatings.
Conventional heat transfer materials result in less than desirable finished products due to the relatively large thickness of the transfer coating. In conventional “hot peel” heat transfer processes, a relatively thick transfer coating layer is required to avoid quality problems, such as splitting of the transfer coating while the base sheet is removed. In conventional “cold peel” heat transfer processes, all of the transfer coating is released from the base sheet, forming a relatively thick coating. Typically, in these processes the transfer coating thickness is at least 40 grams per square meter (gsm). The relatively thick coatings fill the gaps within and between adjacent yarns of the coated fabric, forming bridges over the yarn gaps. The bridges tend to crack when the fabric is washed, resulting in a very poor appearance. Furthermore, the thick transfer coating tends to become sticky when exposed to hot air, such as found in a clothes dryer, such that garments stick together if dried in a hot clothes dryer.
In addition to the problems of cracking and fading of the transferred image-bearing coating, the breathability of the coated article of clothing continues to be a problem using conventional heat transfer coatings. Conventional heat transfer coatings, whether applied using a hot-peelable heat transfer material or a cold-peelable heat transfer material, require a minimal coating thickness in order to produce a continuous image-bearing coating. This results in a finished article of clothing having negligible breathability.
What is needed in the art is a heat transfer material, which substantially resists cracking while maintaining or enhancing the breathability of the coating. What is also needed in the art is a heat transfer material having a heat fusible coating thereon, wherein the heat fusible coating enables the production of a finished, image-bearing, article of clothing having breathability.